In general, a silver halide black and white photographic material is, after imagewise-exposure, processed by the processing steps of black and white development, fixing, washing, etc., and a silver halide color photographic material (hereinafter, referred to as "color photographic material") is, after imagewise-exposure, processed by the processing steps of color development, desilvering, washing, stabilization, etc. Also, a silver halide color reversal photographic material is, after imagewise exposure, processed by the processing steps of black and white development, reversal processing, color development, desilvering, washing, stabilization, etc.
In the color development step for photographic processing, exposed silver halide grains are converted into silver by being reduced with a color developing agent and at the same time, the oxidation product of the color developing agent formed reacts with couplers to form dye images.
Then, in the subsequent desilvering step, developed silver formed by the development step is oxidized into a silver salt by a bleaching agent having an oxidative action (bleach), and further the silver salt is removed from the light-sensitive layer together with remaining silver halide by a fixing agent forming a soluble silver (fix). Bleaching and fixing may be carried out independently as a bleach step and a fix step or may be carried out simultaneously as a bleach-fix (blix) step. Details of the compositions and the processing steps are described in T. H. James, The Theory of Photographic Process, 4th edition, (1977), Research Disclosure, No. 17643, pages 28 to 29, ibid., 18716, page 651, left column to right column, ibid., No. 307105, pages 880 to 881.
In addition to the foregoing fundamental processing steps, various auxiliary steps are added for the purposes of keeping the photographic and physical qualities of dye images and keeping the stability of photographic processing. For example, there are a wash step, a stabilization step, a hardening step, a stop step, etc.
The foregoing processing steps are generally carried out by an automatic processor. Photographic processing is carried out in various places, such as large-scale laboratories, employing large automatic processors. Recently, photo stores have employed small automatic processors called "mini labs". With the increase of such automatic processors, the reduction of the processing power sometimes happens.
One of the large causes of such reduction is entrance of metal ions in the processing solutions.
Various metal ions enter the processing solution through various routes. For example, calcium ions, a magnesium ions, and, in some cases, iron ions enter the processing solution through water being used for preparing the processing solution or calcium ions contained in the gelatin of silver halide photographic materials enters the processing solution. Also, it sometimes happens that by sputtering of a blix solution, an iron chelate contained in the blix solution enters a developer which is the preceding bath. Further, metal ions contained in a preceding bath are carried in by photographic films impregnated with the solution in the preceding bath.
The influences by the intermixed metal ions differ according to the kinds of the metal ions and the processing solution.
For example, calcium ions and magnesium ions in a developer react with a carbonate, which is used as a buffer in the developer, and form precipitates and sludges, which cause the problems of clogging a filter in a circulation system of an automatic processor and in staining photographic films so processed. Also, the entrance of transition metal salts such as iron ions, etc., in a color developer or a black and white developer causes decomposition of a paraphenylenediamine color developing agent, a black and white developing agent, such as hydroquinone, monol (monomethyl-p-aminophenol sulfate), etc., or a preservative, such as hydroxylamine, a sulfite, etc. This results in greatly lowering the photographic characteristics.
Also, when transition metal ions such as iron ions, etc., enter a bleach solution using hydrogen peroxide, persulfate, etc., the stability of the bleach solution is greatly lowered. This causes the problems of inferior bleaching, etc.
Furthermore, when a transition metal salt enters an ordinary fix solution containing a thiosulfate, the stability of the fix solution is lowered. This causes turbidity and sludges in the fix solution. As a result thereof, the filter of the automatic processor is clogged, which reduces the circulating flow amount, whereby fixing becomes inferior, and the photographic films processed become stained. Such a phenomenon in a fix solution also occurs in wash water, which is used subsequent to fixing. In particular, when the amount of wash water is reduced, the exchange ratio of the liquids in the tanks is lowered, whereby the problems of the decomposition of a thiosulfate, which is called sulfiding, and the formation of the precipitations of silver sulfide, are extremely liable to occur.
When such a state occurs, the surface of the photographic film processed is frequently severely stained.
In a stabilization solution prepared using hard water containing a large amount of calcium and magnesium, bacteria grow using calcium and magnesium as a nutrient. This makes the solution turbid and stains the photographic films so processed. Also, when transition metal ions, such as iron ions enter a stabilization solution, the metal ions remain on the surface of a photographic film so processed, thereby the storage stability of the photographic film after processing is deteriorated.
Since, as described above, the entrance of metal ions in processing solutions cause various troubles, effective masking agents for metal ions have been strongly desired.
As a method of solving the foregoing problems, chelating agents capable of masking metal ions have been used. As such chelating agents, there are, for example, the aminopolycarboxylic acids (e.g., ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid) described in JP-B-48-30496 and JP-B-44-30232 (the term "JP-B" as used herein means an "examined Japanese patent publication"), the organic phosphonic acids described in JP-A-56-97347 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"), JP-B-56-39359, and West German Patent 2,227,639, the phosphonocarboxylic acids described in JP-A-52-102726, JP-A-53-42730, JP-A-54-121127, JP-A-55-126241, and JP-A-55-65956, and the compounds described in JP-A-58-195845, JP-A-58-203440, and JP-B-53-40900.
Some of these foregoing compounds are practically used but the performance thereof is yet insufficient. For example, ethylenediaminetetraacetic acid shows a large masking ability to a calcium ions, but when the compound is added to a developer, it accelerates the decomposition of a developing agent and a preservative for the developing agent in the presence of iron ions which causes the deterioration of the photographic characteristics such as lowering of the image density and an increase of the formation of fog. Also, for example, alkylidenediphosphonic acid does not cause such a bad action even in the presence of iron ions but, when this compound is added to a processing solution prepared using hard water having a large content of calcium, solid matters are formed in the solution. This causes a problem for an automatic processor.
In particular, recently, with the increase of the social requirement, of environmental preservation, the replenishing amount of each photographic processing solution tends to be more and more reduced. With the reduction of the replenishing amount, the residence time of each processing solution in the automatic processor is prolonged. Hence, the foregoing deterioration of the storage stability becomes a larger problem than in conventional cases.
Accordingly, the development of an excellent novel chelating agent which can effectively mask metal ions accumulated in a processing solution without causing any problems has been strongly desired.
Also, with the increase of the use of mini labs for processing of color photographic materials, a quick processing service for customers has been increased.
However, ethylenediaminetetraacetic acid ferric complex salt, which is conventionally used as a bleaching agent for a bleach step and/or a blix step in processing of color photographic materials, has a fundamental fault in that the oxidative power is weak. In spite of that the improvement such as the use of a bleach accelerator (e.g., the addition of the mercapto compound described in U.S. Pat. No. 1,138,842), etc., is added. However, quick bleaching has not yet been attained.
As a bleaching agent capable of attaining quick bleaching, potassium ferricyanide, iron chloride, bromates, etc., are known. However, potassium ferricyanide can not be widely used because of environmental concerns, iron chloride can not be widely used because of its inconvenience in handling, such as the corrosion of metals, etc., and bromates can not be widely used because of the problem of instability of the processing solution.
Accordingly, a bleaching agent capable of attaining quick bleaching having a good handling property without causing the problem at discharging the waste solution has been desired. Recently, as a bleaching agent meeting such requirements, 1,3-diaminopropanetetraacetic acid ferric complex salt has been disclosed as a bleaching agent.
However, the foregoing bleaching agent has a problem in performance, such as bleach fog forming with bleaching. As a method of reducing the formation of the bleach fog, it is disclosed to add a buffer to the bleach solution as described, e.g., in JP-A-1-213657. However, the improvement level is not sufficiently satisfactory. In particular, since a developer having a high activity is used in quick processing wherein the color development is carried out within 3 minutes, large bleach fog occurs even in the case of using such a buffer.
Furthermore, when the processing solution having a bleaching power containing the 1,3-diaminopropanetetraacetic acid ferric complex salt is used, there occurs a problem that during storing the photographic images after processing, the formation of stain is increased.
Moreover, when continuous processing is carried out using a processing solution having a bleaching power containing the 1,3-diaminopropanetetraacetic acid ferric complex salt, there occur the problems that the desilvering property is greatly lowered as compared with the beginning of continuous processing. Also, precipitates form in the processing solution.
Thus, a novel processing composition having a bleaching power and a processing process, which can be employed without causing the foregoing problems, have been desired.